A Meta-Analysis of the Effect of Forest Management for Timber on Understory Plant Species Diversity in Temperate Forests. Duguid, M. C. and Ashton, M. S. 303:81–90.
A Meta-Analysis of the Effect of Forest Management for Timber on Understory Plant Species Diversity in Temperate Forests [link]Paper  doi  abstract   bibtex   
[Highlights] [::] We synthesized data from 100 studies to examine understory response to forest harvesting. [::] Across all studies there was no significant effect from timber harvesting on understory richness. [::] Selection harvesting had a positive effect on understory species richness. [::] Even-aged silvicultural treatments showed effects after 50 years or more, while early successional stages did not. [::] Thinning treatments had no effect on understory richness. [Abstract] Many studies have examined affects of forest management – particularly regeneration treatments – for timber on understory plant diversity. These studies taken independently show no clear trends in diversity with degree and/or periodicity of disturbance from timber harvests. Here we present a meta-analysis synthesizing primary field research on response of understory plant diversity to timber harvesting in temperate forests, particularly in North America. Across a pool of 96 studies, we find no effect on understory plant species richness from managing forests for timber. When intensive regeneration harvests (e.g. clearcut, shelterwood) are separated from less intensive regeneration harvests (e.g. single tree and group selection systems) and thinnings, selection harvests show a positive effect on species richness. Intensive regeneration harvests and thinning treatments had no effect on species richness. We examined the role of stand development following regeneration treatments, and found no detectable effects on species richness for even-aged stands within the first 50 years after clearcut and shelterwood timber harvests. Stands in later successional stages, however, had lower species richness than un-logged stands. All these findings together suggest that silvicultural activities focused toward timber management are not inconsistent with conservation of understory plant diversity. We suggest site-specific characteristics (e.g. resource availability, resource heterogeneity) at various temporal and spatial scales, have a larger role to play in defining understory plant diversity than the disturbance of harvesting itself. Managers therefore should consider underlying factors of site and species composition, and should examine regionally specific studies when planning silvicultural treatments. In addition, it should be noted that our analysis makes no distinction in classifying the nature of diversity, especially between colonizing early-successional species that peak after 1-10 years and then disappear, and late successional, often more site specific and shade tolerant species, that may persist post harvest but often disappear or retract in their range and abundance. Further studies are needed to tease out differences in diversity in relation to successional stage and affects of forest management. [Excerpt:Meta-analysis] Firstly, across all studies, irrespective of silvicultural treatment (clearcut, shelterwood, selection, thinning) or successional stage, timber harvesting had no clear influence on understory plant richness [...]. The effect size measure by the response ratio indicates a slight increase of 4.9\,% [...] in understory species diversity under forest management as compared to unmanaged, but this increase is not significant [...] [\n] Secondly, the only silvicultural treatment with a positive effect on understory richness was selection [...], with a 30\,% [...] increase in understory plant diversity as calculated by the response ratio. Both even-aged regeneration methods (clearcut, shelterwood) [...] and thinning [...] had no significant effects detected. Studies within each treatment category, however, showed considerable variation with positive, negative, or no significant difference [...] [\n] Lastly, when we included the grouping factor of successional stage within the even-aged regeneration methods we found stands in later successional stages had lower species richness than unharvested controls [...], a 28.4\,% decrease [...] in understory species richness from the controls. [...] [\n] [...]
@article{duguidMetaanalysisEffectForest2013,
  title = {A Meta-Analysis of the Effect of Forest Management for Timber on Understory Plant Species Diversity in Temperate Forests},
  author = {Duguid, Marlyse C. and Ashton, Mark S.},
  date = {2013-09},
  journaltitle = {Forest Ecology and Management},
  volume = {303},
  pages = {81--90},
  issn = {0378-1127},
  doi = {10.1016/j.foreco.2013.04.009},
  url = {https://doi.org/10.1016/j.foreco.2013.04.009},
  abstract = {[Highlights]

[::] We synthesized data from 100 studies to examine understory response to forest harvesting.

[::] Across all studies there was no significant effect from timber harvesting on understory richness.

[::] Selection harvesting had a positive effect on understory species richness.

[::] Even-aged silvicultural treatments showed effects after 50 years or more, while early successional stages did not.

[::] Thinning treatments had no effect on understory richness.

[Abstract]

Many studies have examined affects of forest management -- particularly regeneration treatments -- for timber on understory plant diversity. These studies taken independently show no clear trends in diversity with degree and/or periodicity of disturbance from timber harvests. Here we present a meta-analysis synthesizing primary field research on response of understory plant diversity to timber harvesting in temperate forests, particularly in North America. Across a pool of 96 studies, we find no effect on understory plant species richness from managing forests for timber. When intensive regeneration harvests (e.g. clearcut, shelterwood) are separated from less intensive regeneration harvests (e.g. single tree and group selection systems) and thinnings, selection harvests show a positive effect on species richness. Intensive regeneration harvests and thinning treatments had no effect on species richness. We examined the role of stand development following regeneration treatments, and found no detectable effects on species richness for even-aged stands within the first 50 years after clearcut and shelterwood timber harvests. Stands in later successional stages, however, had lower species richness than un-logged stands. All these findings together suggest that silvicultural activities focused toward timber management are not inconsistent with conservation of understory plant diversity. We suggest site-specific characteristics (e.g. resource availability, resource heterogeneity) at various temporal and spatial scales, have a larger role to play in defining understory plant diversity than the disturbance of harvesting itself. Managers therefore should consider underlying factors of site and species composition, and should examine regionally specific studies when planning silvicultural treatments. In addition, it should be noted that our analysis makes no distinction in classifying the nature of diversity, especially between colonizing early-successional species that peak after 1-10 years and then disappear, and late successional, often more site specific and shade tolerant species, that may persist post harvest but often disappear or retract in their range and abundance. Further studies are needed to tease out differences in diversity in relation to successional stage and affects of forest management.

[Excerpt:Meta-analysis]

Firstly, across all studies, irrespective of silvicultural treatment (clearcut, shelterwood, selection, thinning) or successional stage, timber harvesting had no clear influence on understory plant richness [...]. The effect size measure by the response ratio indicates a slight increase of 4.9\,\% [...] in understory species diversity under forest management as compared to unmanaged, but this increase is not significant [...]

[\textbackslash n] Secondly, the only silvicultural treatment with a positive effect on understory richness was selection [...], with a 30\,\% [...] increase in understory plant diversity as calculated by the response ratio. Both even-aged regeneration methods (clearcut, shelterwood) [...] and thinning [...] had no significant effects detected. Studies within each treatment category, however, showed considerable variation with positive, negative, or no significant difference [...]

[\textbackslash n] Lastly, when we included the grouping factor of successional stage within the even-aged regeneration methods we found stands in later successional stages had lower species richness than unharvested controls [...], a 28.4\,\% decrease [...] in understory species richness from the controls. [...]

[\textbackslash n] [...]},
  keywords = {*imported-from-citeulike-INRMM,~INRMM-MiD:c-14068436,~to-add-doi-URL,biodiversity,diversity,forest-management,forest-resources,species-richness,temperate-forests,understorey}
}
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